U.S. patent application number 13/233968 was filed with the patent office on 2012-01-12 for ring-shaped component for use in a plasma processing, plasma processing apparatus and outer ring-shaped member.
This patent application is currently assigned to TOKYO ELECTRON LIMITED. Invention is credited to Takahiro Murakami, Nobuhiro Sato.
Application Number | 20120006488 13/233968 |
Document ID | / |
Family ID | 37828978 |
Filed Date | 2012-01-12 |
United States Patent
Application |
20120006488 |
Kind Code |
A1 |
Murakami; Takahiro ; et
al. |
January 12, 2012 |
RING-SHAPED COMPONENT FOR USE IN A PLASMA PROCESSING, PLASMA
PROCESSING APPARATUS AND OUTER RING-SHAPED MEMBER
Abstract
A ring-shaped component for use in a plasma processing includes
an inner ring-shaped member provided to surround an outer periphery
of a substrate to be subjected to the plasma processing and an
outer ring-shaped member provided to surround an outer periphery of
the inner ring-shaped member. The outer ring-shaped member has a
first surface facing a processing space side and a second surface
facing an opposite side of the plasma generation side. The second
surface has thereon one or more ring-shaped grooves.
Inventors: |
Murakami; Takahiro;
(Nirasaki-shi, JP) ; Sato; Nobuhiro; (Miyagi-gun,
JP) |
Assignee: |
TOKYO ELECTRON LIMITED
Minato-ku
JP
|
Family ID: |
37828978 |
Appl. No.: |
13/233968 |
Filed: |
September 15, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
11511404 |
Aug 29, 2006 |
8038837 |
|
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13233968 |
|
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|
60722991 |
Oct 4, 2005 |
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Current U.S.
Class: |
156/345.29 ;
118/723E; 156/345.43 |
Current CPC
Class: |
H01J 37/32642
20130101 |
Class at
Publication: |
156/345.29 ;
156/345.43; 118/723.E |
International
Class: |
C23F 1/08 20060101
C23F001/08; C23C 16/458 20060101 C23C016/458; C23C 16/50 20060101
C23C016/50; C23C 16/455 20060101 C23C016/455 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2005 |
JP |
2005-255179 |
Claims
1. A mounting table for mounting thereon a substrate comprising: a
lower electrode to which a high frequency power is supplied to
generate a plasma to thereby process the substrate; an
electrostatic chuck for adsorbing the substrate thereto by using an
electrostatic adsorptive force, wherein the electrostatic chuck is
disposed on the lower electrode and a diameter of the electrostatic
chuck is smaller than a diameter of the substrate; an electrode
plate disposed in the electrostatic chuck; an inner ring-shaped
member provided on the lower electrode to surround the
electrostatic chuck, a part of the lower electrode, and an outer
periphery of the substrate; an outer ring-shaped member provided to
surround an outer periphery of the inner ring-shaped member; and a
covering member provided to surround the lower electrode and the
outer periphery of the inner ring-shaped member, wherein the outer
ring-shaped member includes a plurality of stacked plates having:
an upper ring-shaped plate having an upper surface facing a
processing space where the substrate is processed, and a lower
ring-shaped plate mounting thereon the upper ring-shaped plate, the
lower ring-shaped plate being mounted on the covering member.
2. The mounting table of claim 1, wherein the upper ring-shaped
plate has a thickness of about 1.5 mm to about 2.0 mm.
3. The mounting table of claim 1, wherein the outer ring-shaped
member is formed of at least one of quartz, carbon, silicon, and
ceramic.
4. The mounting table of claim 1, wherein a plurality of
protrusions is formed on a lower surface of the upper ring-shaped
plate via which the lower surface of the upper ring-shaped plate is
in point contact with the lower ring-shaped plate.
5. The mounting table of claim 1, wherein a contact area between
the upper and the lower ring-shaped plate is equal to or smaller
than 1% of a surface area of a lower surface of the upper
ring-shaped plate.
6. The mounting table of claim 1, wherein a number of the stacked
plates is three.
7. The mounting table of claim 4, wherein a contact area between
the upper and the lower ring-shaped plate is equal to or smaller
than 1% of a surface area of the lower surface of the upper
ring-shaped plate.
8. A plasma processing apparatus comprising: a processing chamber
wherein a plasma processing is performed on a substrate; a mounting
table for mounting thereon the substrate, the mounting table being
disposed in the processing chamber; a gas supply member for
supplying a gas into the processing chamber; a gas exhaust port for
exhausting air inside the processing chamber with the help of a
pump, wherein the mounting table includes: a lower electrode to
which a high frequency power is supplied to generate a plasma to
thereby process the substrate, an electrostatic chuck for adsorbing
the substrate thereto by using an electrostatic adsorptive force,
wherein the electrostatic chuck is disposed on the lower electrode
and a diameter of the electrostatic chuck is smaller than a
diameter of the substrate, an electrode plate disposed in the
electrostatic chuck, an inner ring-shaped member provided on the
lower electrode to surround the electrostatic chuck, a part of the
lower electrode, and an outer periphery of the substrate, an outer
ring-shaped member provided to surround an outer periphery of the
inner ring-shaped member, and a covering member provided to
surround the lower electrode and the outer periphery of the inner
ring-shaped member, and wherein the outer ring-shaped member
includes a plurality of stacked plates having: an upper ring-shaped
plate having an upper surface facing a processing space where the
substrate is processed; and a lower ring-shaped plate mounting
thereon the upper ring-shaped plate, the lower ring-shaped plate
being mounted on the covering member.
9. The plasma processing apparatus of claim 8, wherein the upper
ring-shaped plate has a thickness of about 1.5 mm to about 2.0
mm.
10. The plasma processing apparatus of claim 8, wherein the outer
ring-shaped member is formed of at least one of quartz, carbon,
silicon and ceramic.
11. The plasma processing apparatus of claim 8, wherein a plurality
of protrusions is formed on a lower surface of the upper
ring-shaped plate via which the lower surface of the upper
ring-shaped plate is in point contact with the lower ring-shaped
plate.
12. The plasma processing apparatus of claim 8, wherein a contact
area between the upper and the lower ring-shaped plate is equal to
or smaller than 1% of a surface area of a lower surface of the
upper ring-shaped.
13. The plasma processing apparatus of claim 8, wherein a number of
the stacked plates is three.
14. The plasma processing apparatus of claim 11, wherein a contact
area between the upper and the lower ring-shaped plate is equal to
or smaller than 1% of a surface area of the lower surface of the
upper ring-shaped plate
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 11/511,404, filed on Aug. 29, 2006, the entire contents of
which is incorporated herein by reference. U.S. application Ser.
No. 11/511,404 claims the benefit of priority under 119(e) of U.S.
Provisional Application No. 60/722,991, filed Oct. 4, 2005, and
claims the benefit of priority under 35 U.S.C. .sctn.119 to
Japanese Patent Application No. 2005-255179, filed on Sep. 2,
2005.
FIELD OF THE INVENTION
[0002] The present invention relates to a ring-shaped component for
use in a plasma processing, a plasma processing apparatus and an
outer ring- shaped member; and, more particularly, to a ring-shaped
component for use in a plasma processing, surrounding an outer
periphery of a substrate to be subjected to the plasma processing
in a processing chamber.
BACKGROUND OF THE INVENTION
[0003] In general, a plasma processing apparatus for performing a
plasma processing on a circular plate shaped wafer includes a
processing chamber for accommodating therein the wafer, a shower
head for supplying a processing gas into the processing chamber and
a mounting table for mounting thereon the wafer. The mounting table
is connected to a high frequency power supply and serves as an
electrode for applying a high frequency power into the processing
chamber. Such a plasma processing apparatus performs a plasma
processing on the wafer by using ions and/or radicals generated by
converting the processing gas supplied to the processing chamber
into a plasma with the high frequency power applied thereto.
[0004] Further, the plasma processing apparatus has a ring-shaped
focus ring installed to surround an outer periphery of the wafer
mounted on the mounting table in the processing chamber. The focus
ring has a double ring structure, including a ring-shaped inner
focus ring member provided at an inner portion and a ring-shaped
outer focus ring member provided to surround an outer periphery of
the inner focus ring member. The inner focus ring member is made of
a conductive material such as silicon or the like, whereas the
outer focus ring member is made of an insulating material such as
quartz or the like. The inner focus ring member concentrates or
collects the plasma on the wafer, and the outer focus ring member
serves as an insulator for confining the plasma on the wafer.
[0005] During the plasma processing, the temperature of the outer
focus ring member increases due to a heat from the plasma. However,
if the temperature thereof is unstably maintained, an ion and/or a
radical density near the outer focus ring member becomes
non-uniform, causing the ion and/or radical density in an outer
peripheral portion of the wafer to also become non-uniform.
Consequently, the central and the peripheral portion of the wafer
are plasma-processed differently, which makes it difficult to carry
out a uniform plasma processing on the wafer. In addition, as a
consequence of the outer focus ring member being scaled up to meet
a recent trend for the larger diameter wafer, the temperature
rising rate of the outer focus ring member decreases, requiring
more time for the temperature to reach a specific value and remain
stable thereat. As a result, it becomes difficult to perform a
uniform plasma processing on the wafer, which in turn deteriorates
a production yield.
[0006] To this end, recently, there is developed an outer focus
ring member having therein a heater (see, e.g., Japanese Patent
Laid-open Application No. 2000-36490 (hereinafter, referred to as
"Patent Document"). In such an outer focus ring member, the
temperature thereof can be stably maintained rather rapidly by
controlling the heater, allowing a uniform plasma processing to be
performed on the wafer.
[0007] In a plasma processing apparatus, dummy wafer are generally
processed first with a recipe identical to that to be used in an
actual production lot processing in order to stabilize an inner
atmosphere of a processing chamber prior to starting the production
lot processing. However, during the processing of the dummy wafers,
deposits, i.e., reaction products of the processing gas, get
deposited on the surface of the outer focus ring member if the
temperature thereof has not increased enough. As the production lot
processing continues, the deposits gradually get peeled off and
then get adhered to the wafer as particles, which in turn
detrimentally affects the production yield of the wafer.
Accordingly, there arises a need to shorten a cleaning process
cycle for removing the deposits from the outer focus ring
member.
[0008] In the technical field of a CVD(chemical vapor deposition)
plasma processing apparatus, it is well known that deposits can be
removed fast by increasing the temperature of the member to which
the deposits are adhered and the member can also be maintained in a
condition where deposits can hardly be produced by maintaining the
member at a high temperature. In case of using outer focus ring
member of the aforementioned Patent Document, the deposits can be
removed from the outer focus ring member by increasing the
temperature of the outer focus ring member by controlling the
heater. And then, the member can also be maintained in a condition
where deposits can hardly be produced, which can prevent particles
from adhering to the wafer and, also, a cleaning cycle can be
lengthened.
[0009] The outer focus ring member is consumed by ions or the like
colliding therewith during the plasma processing, requiring it to
be regularly replaced. Since, however, the manufacturing cost as
well as the running cost of using the outer focus ring member of
the Patent Document is high because of the heater embedded therein.
Further, a required wiring process of the heater complicates the
replacement of the member and deteriorates the maintenability. It
is also necessary to provide wiring for the heater in the mounting
table. For such reasons, the outer focus ring member of the Patent
Document may not be readily adopted.
SUMMARY OF THE INVENTION
[0010] It is, therefore, an object of the present invention to
provide an easily usable ring-shaped component for use in a plasma
processing, a plasma processing apparatus and an outer ring-shaped
member capable of avoiding deterioration of a wafer production
yield and lengthen a cleaning cycle.
[0011] In accordance with a first aspect of the present invention,
there is provided a ring-shaped component for use in a plasma
processing, including: an inner ring-shaped member provided to
surround an outer periphery of a substrate to be subjected to the
plasma processing; and an outer ring-shaped member provided to
surround an outer periphery of the inner ring-shaped member,
wherein the outer ring-shaped member has a first surface facing a
plasma generation space side where a plasma is generated and a
second surface facing an opposite side of the plasma generation
space side, the second surface having thereon at least one
ring-shaped groove.
[0012] Preferably, a thickness between the first surface and a
bottom portion of the groove is about 1.5 mm to about 2.0 mm.
[0013] Preferably, the outer ring-shaped member is formed of at
least any one of quartz, carbon, silicon and ceramic.
[0014] In accordance with a second aspect of the present invention,
there is provided a ring-shaped component for use in a plasma
processing, including: an inner ring-shaped member provided to
surround an outer periphery of a substrate to be subjected to the
plasma processing; and an outer ring-shaped member provided to
surround an outer periphery of the inner ring-shaped member,
wherein the outer ring-shaped member is formed of at least two
laminated ring-shaped plates.
[0015] Preferably, among the laminated ring-shaped plates, a
ring-shaped plate provided at a plasma generation space side has a
thickness of about 1.5 mm to about 2.0 mm.
[0016] Preferably, the outer ring-shaped member of the second
aspect of the present invention is formed of at least any one of
quartz, carbon, silicon and ceramic.
[0017] In accordance with a third aspect of the present invention,
there is provided a plasma processing apparatus including: the
ring-shaped component of the first aspect; and a processing chamber
wherein the plasma processing is performed on the substrate.
[0018] In accordance with a fourth another aspect of the present
invention, there is provided a plasma processing apparatus
including: the ring-shaped component of the second aspect; and a
processing chamber wherein the plasma processing is performed on
the substrate.
[0019] In accordance with a fifth aspect of the present invention,
there is provided an outer ring-shaped member provided to surround
an outer periphery of an inner ring-shaped member provided to
surround an outer periphery of a substrate to be subjected to a
plasma processing, the outer ring-shaped member including: a first
surface facing a plasma generation space side where a plasma is
generated; and a second surface facing an opposite side of the
plasma generation space side, the second surface having thereon at
least one ring-shaped groove.
[0020] In accordance with a sixth aspect of the present invention,
there is provided an outer ring-shaped member provided to surround
an outer periphery of an inner ring-shaped member provided to
surround an outer periphery of a substrate to be subjected to a
plasma processing, wherein the outer ring-shaped member is formed
of at least two laminated ring-shaped plates.
[0021] In accordance with the ring-shaped component of the first
aspect of the present invention, a plasma processing apparatus of
the third aspect, and an outer ring-shaped member of the fifth
aspect of the present invention, at least one ring-shaped groove is
formed on the second surface of the outer ring-shaped member facing
an opposite side of the plasma generation space side.
Therefore, the heat capacity of the outer ring-shaped member can be
small and thus it is possible to sharply increase the temperature
thereof by absorbing heat from the plasma and further to easily
maintain the high temperature. As a result, the deposits adhered to
the outer ring-shaped member can be rapidly removed and, also, the
state in which the deposits are hardly deposited can be maintained.
Accordingly, it is possible to avoid deterioration of a substrate
production yield and lengthen a cleaning cycle of the ring-shaped
component for use in a plasma processing. Further, only the ring
groove is formed on the second surface in the outer ring-shaped
member, which is a simple machining process. Thus, the outer
ring-shaped member can be manufactured at a low cost, allowing a
running cost to be reduced. Moreover, since the outer focus ring
member can be easily replaced, it is possible to avoid a
deterioration of the maintenability. Consequently, the ring-shaped
component can be easily adopted.
[0022] In accordance with the ring-shaped component of the first
aspect of the present invention, the thickness between the first
surface of outer ring-shaped member and the bottom portion of the
groove is from about 1.5 mm to about 2.0 mm, ensuring the stiffness
of the outer ring-shaped member to be preserved to thereby prevent
the outer ring-shaped member from being damaged.
[0023] In accordance with the ring-shaped component of the first
aspect of the present invention, the outer ring-shaped member is
formed of at least any one of quartz, carbon, silicon and ceramic.
Thus, the outer ring-shaped member can be manufactured at a low
cost, and the ring-shaped component can be easily adopted.
[0024] In accordance with the ring-shaped component of the second
aspect of the present invention, the plasma processing apparatus of
the fourth aspect of the present invention and the outer
ring-shaped member of the sixth aspect of the present invention,
the outer ring-shaped member is formed of at least two laminated
ring-shaped plates. Therefore, the heat capacity of a ring-shaped
plate disposed at the plasma generation space side can be small and
thus it is possible to sharply increase the temperature thereof by
absorbing heat from the plasma and further to easily maintain the
high temperature. As a result, the deposits adhered to the
corresponding ring-shaped plate can be rapidly removed in the
earliest processing stage and, also, the state in which the
deposits are hardly deposited can be maintained. Accordingly, it is
possible to avoid deterioration of a substrate production yield and
lengthen a cleaning cycle. Further, only plural ring-shaped plates
are laminated in the outer ring-shaped member, a configuration
thereof is simple. Thus, the outer ring-shaped member can be
manufactured at a low cost, allowing the running cost to be
reduced. Moreover, since the outer ring-shaped member can be easily
replaced, it is possible to avoid a deterioration of the
maintenability. Consequently, the ring-shaped component for use in
a plasma processing can be easily adopted.
[0025] In accordance with the ring-shaped component of the second
aspect of the present invention, the ring-shaped plate provided at
a plasma generation space side has a thickness of about 1.5 mm to
about 2.0 mm, ensuring the stiffness of the corresponding
ring-shaped plate to be preserved to thereby prevent the
corrresponding ring-shaped plate from being damaged.
[0026] In accordance with the ring-shaped component of the second
aspect of the present invention, the outer ring-shaped member is
formed of at least any of quartz, carbon, silicon and ceramic.
Thus, the outer ring-shaped member can be manufactured at a low
cost, and the ring-shaped component can be easily adopted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The above and other objects and features of the present
invention will become apparent from the following description of
preferred embodiments, given in conjunction with the accompanying
drawings, in which:
[0028] FIG. 1 is a schematic cross sectional view of a plasma
processing apparatus employing a focus ring as a ring-shaped
component for use in a plasma processing in accordance with a first
preferred embodiment of the present invention;
[0029] FIG. 2 describes an enlarged cross sectional view of a
peripheral portion of the focus ring of FIG. 1;
[0030] FIG. 3 provides an enlarged cross sectional view of a
peripheral portion of a focus ring employed in the plasma
processing apparatus as a ring-shaped component for use in a plasma
processing in accordance with a second preferred embodiment of the
present invention;
[0031] FIGS. 4A and 4B present enlarged cross sectional views of
modified example of the focus rings employed as the ring-shaped
components for use in a plasma processing in accordance with the
first and the second preferred embodiment of the present invention,
respectively;
[0032] FIG. 5 represents a graph illustrating a relationship
between a high frequency power application elapsed time and the
number of measured particles in case of using the focus ring as the
ring-shaped component for use in the plasma processing in
accordance with the second preferred embodiment of the present
invention;
[0033] FIG. 6 offers a graph describing a relationship between a
high frequency power application elapsed time and the number of
measured particles in case of using a conventional focus ring;
and
[0034] FIG. 7 provides a schematic cross sectional view of a plasma
processing apparatus employing a shield ring as a ring-shaped
component for use in the plasma processing in accordance with
another preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0035] Hereinafter, preferred embodiments of the present invention
will be described with reference to the accompanying drawings.
[0036] First of all, the following is a description on a plasma
processing apparatus employing a ring-shaped component for use in a
plasma processing in accordance with a first preferred embodiment
of the present invention.
[0037] FIG. 1 is a schematic cross sectional view of a plasma
processing apparatus employing a focus ring as a ring-shaped
component for use in the plasma processing in accordance with the
first preferred embodiment of the present invention.
[0038] Referring to FIG. 1, a plasma processing apparatus 10
configured as an etching processing apparatus for performing a
plasma processing, e.g., a reactive ion etching, on a wafer W for
producing semiconductor devices has a chamber 11 serving as a
processing chamber made of a metal such as aluminum or stainless
steel.
[0039] Installed inside the chamber 11 are a lower electrode
serving as a mounting table (wafer stage) for mounting thereon the
wafer W having a diameter of, for example, 300 mm, and a shower
head 13 provided on a ceiling portion of the chamber 11 to face the
lower electrode 12. The lower electrode 12 vertically moves inside
the chamber 11 with the wafer W mounted thereon, and the shower
head 13 supplies a processing gas to be described later into the
chamber 11.
[0040] A lower high frequency power supply 14 is connected to the
lower electrode 12 via a lower matching unit (LMU) 15 and supplies
a high frequency power to the lower electrode 12. Further, the
lower matching unit 15 maximizes an incidence efficiency of the
high frequency power on the lower electrode 12 by reducing a
reflection of the high frequency power from the lower electrode
12.
[0041] Provided on the lower electrode 12 is an ESC (electrostatic
chuck) 16 for adsorbing the wafer W thereto by using an
electrostatic adsorptive force. The ESC 16 has therein an ESC
electrode plate 17 formed of laminated electrode films, and a DC
power supply 18 is electrically connected to the ESC electrode
plate 17. Further, the ESC 16 adsorbs and holds the wafer W on a
top surface thereof by the Coulomb force or the Johnson-Rahbek
force generated by a DC voltage supplied from the DC power supply
18 to the ESC electrode plate 17.
[0042] Installed around the wafer W mounted on the ESC 16 is a
circular ring-shaped focus ring 19 (ring-shaped component for use
in a plasma processing) to surround an outer periphery of the wafer
W. The focus ring 19 has a circular ring-shaped inner focus ring
member 20 provided to surround an outer periphery of the mounted
wafer W and a circular ring-shaped outer focus ring member 21
provided to surround an outer periphery of the inner focus ring
member 20. The inner focus ring member 20 is mounted on the lower
electrode 12, and the outer focus ring member 21 is mounted on an
ESC covering member 22 provided to surround the lower electrode 12.
The inner focus ring member 20 is made of a conductive material
such as silicon or the like, whereas the outer focus ring member is
made of an insulating material such as quartz or the like. The
inner focus ring member 20 serves to collect on the wafer W a
plasma generated in a processing space S (plasma generation space)
between the lower electrode 12 and the shower head 13 and the outer
focus ring member 21 serves as an insulator for confining the
plasma on the wafer W. A shape of the outer focus ring member 21
will be described later in detail.
[0043] Provided under the lower electrode 12 is a support 23
downwardly extending from a lower surface of the lower electrode
12. The support 23 supports lower electrode 12, which is elevated
by rotating a ball screw (not shown). Further, since a periphery of
the support 23 is covered by covers 24 and 25, the support 23 is
isolated from an inner atmosphere of the chamber 11.
[0044] Installed on a sidewall of the chamber 11 are a
loading/unloading port 26 of the wafer W and a gas exhaust port 27.
The wafer W is loaded into and unloaded from the chamber 11 via the
loading/unloading port 26 by a transfer arm (not shown) of a LLM
(load lock module) (not shown) provided near the plasma processing
apparatus 10. The gas exhaust port 27 is connected to a gas exhaust
system having an APC (automatic pressure control) valve, a DP (dry
pump), a TMP (turbo molecular pump) or the like (all not shown) and
exhausts air inside the chamber 11 or the like to the outside.
[0045] In such a plasma processing apparatus 10, when loading the
wafer W into the chamber 11, the lower electrode 12 is lowered to a
height equal to that of the loading/unloading port 26. Further,
when plasma processing the wafer W, the lower electrode 12 is
raised to a processing position of the wafer W. FIG. 1 shows a
positional relationship between the loading/unloading port 26 and
the lower electrode 12 when the wafer W is loaded into the chamber
11.
[0046] Further, the shower head 13 includes a circular plate shaped
upper electrode plate 29 having a plurality of gas holes 28 facing
the processing space S and an electrode plate support 30 installed
on the upper electrode plate 29 to attachably and detachably
support same. Further, an outer peripheral portion of a surface of
the upper electrode plate 29 facing the processing space S is
covered by an inner peripheral portion of a circular ring-shaped
member provided on the ceiling portion of the chamber 11 as a
shield ring 35. The shield ring 35 is made of quartz or the like,
for example, and protects, from the plasma, screws(not shown)
installed at an outer peripheral portion of the upper electrode
plate 29 to fasten same to the ceiling portion of the chamber 11
from the plasma.
[0047] An upper high frequency power supply 31 is connected to the
upper electrode plate 29 via an upper matching unit (UMU) 32 and
supplies a high frequency power to the upper electrode plate 29.
Further, the upper matching unit 32 maximizes an incidence
efficiency of the high frequency power on the upper electrode plate
29 by reducing a reflection of the high frequency power from the
upper electrode plate 29.
[0048] A buffer chamber 33 is provided inside the electrode plate
support 30 and connected with a processing gas inlet line (not
shown). A processing gas containing CF.sub.4, O.sub.2 and Ar, for
example, is introduced into the buffer chamber 33 through the
processing gas inlet line and then supplied into the processing
space S via the gas holes 28.
[0049] As described above, ions and/or radicals are generated in
the chamber 11 of the plasma processing apparatus 10 by generating
a high density plasma from the processing gas in the processing
space S with the high frequency powers supplied to the lower
electrode 12 and the upper electrode plate 29. The ions and/or
radicals thus generated are collected on a surface of the wafer W
by the focus ring 19 and used for physically or chemically etching
the surface of the wafer W.
[0050] In such a plasma processing apparatus 10, a plasma
processing of a dummy wafer is performed prior to a processing for
a production lot of the wafers. In order to perform the plasma
processing of the dummy wafer, the dummy wafer is loaded into the
chamber 11 and, then, a plasma is generated from a processing gas
introduced into the chamber 11 according to a preset recipe. By
performing the plasma processing on the dummy wafer as described
above, the inner atmosphere of the chamber 11 can be stabilized.
During the process, reaction products are generated by chemical
reactions between the plasma of the processing gas and materials
existing on the surface of the dummy wafer. However, the outer
focus ring member 21 insufficiently absorbs heat from the plasma
and thus has a low temperature, a large amount of the generated
reaction products are adhered to the surface of the outer focus
ring as deposits. Such deposits get peeled off and then adhered
onto the wafer as particles, thereby deteriorating the production
yield of the wafer. To that end, there arises a need to remove the
deposits at the earliest processing stage of the production lot and
then maintain a state in which the deposits get hardly deposited.
The recipe of the plasma processing for the dummy wafer may be
identical to or different from that of the plasma processing for
the production lot.
[0051] As described above, there is known in the field of the
[0052] CVD processing apparatus that by raising the temperature of
the member to which the deposits are adhered, it is possible to
remove the deposits and maintain a state in which the deposits get
hardly deposited. Therefore, in order to check whether or not the
same effects can be obtained from the etching processing apparatus,
the present inventor has observed a relationship between a plasma
processing time (high frequency power application elapsed time) and
the amount of deposits adhered to the outer focus ring member in
case of using the plasma processing apparatus 10 employing a
conventional outer focus ring member instead of the outer focus
ring member 21. As a result, it was found that the amount of
deposits adhered in large quantity by the plasma processing of the
dummy wafer decreases as the high frequency power application
elapsed time increases and then are mostly removed 25 hours
later.
[0053] In the plasma processing, since the temperature of the outer
focus ring member increases by the heat absorbed from the plasma,
the longer the high frequency power application elapsed time is,
the longer a period of time in which the outer focus ring member is
maintained at a high temperature is. In other words, the longer the
period of time in which the outer focus ring member is maintained
at the high temperature is, the less the amount of deposits adhered
to the outer focus ring member is. Accordingly, the present
inventor has found that by raising the temperature of the member
(outer focus ring member) to which the deposits are adhered, it is
also possible in the etching processing apparatus to remove the
deposits and maintain a state in which the deposits are hardly
deposited. Moreover, based on the information in which the deposits
can be removed by increasing the temperature of the outer focus
ring member, the present inventor has inferred that the deposits
can be rapidly removed by rapidly increasing the temperature of the
outer focus ring member.
[0054] Hence, the outer focus ring member 21 of this embodiment has
a structure enabling a rapid temperature increase, which will be
described hereinafter.
[0055] FIG. 2 is an enlarged cross sectional view around the focus
ring 19 in FIG. 1.
[0056] Referring to FIG. 2, the outer focus ring member 21 is a
circular ring-shaped flat plate member made of, e.g., quartz and
includes a plasma exposure surface 21a (first surface) facing the
processing space S side and a covering member contact surface 21b
(second surface) facing the opposite side of the processing space S
while being in contact with the ESC covering member 22. Formed on
the covering member contact surface 21b of the outer focus ring
member 21 is a ring groove 34 having a ring shape concentric with
the outer focus ring member 21. The ring groove 34 has a
rectangular cross sectional shape and is formed by a counter
boring.
[0057] By graving the aforementioned ring groove 34, there are
formed in the outer focus ring member 21 has a thin portion and two
thick portions respectively surrounding an inner side and an outer
side of the thin portion. A thickness of the thin portion, i.e., a
thickness t between a bottom portion 34a of the ring groove 34 and
the plasma exposure surface 21a is set to be between about 1.5 mm
and about 2.0 mm. Further, a thickness of the thick portion, i.e.,
a thickness between the plasma exposure surface 21a and the
covering member contact surface 21b is set to be about 3.5 mm. Due
to the presence of the thin portion, the outer focus ring member 21
has a smaller volume compared with the conventional outer focus
ring member and thus has a smaller heat capacity.
[0058] Since the outer focus ring member 21 is made by cutting a
pure quartz material, its surface is not smooth but it has a rough
surface covered with fine protrusions formed thereby. Therefore,
the covering member contact surface 21b is in, e.g., point contact
with the ESC covering member 22 via the multiple protrusions
without being in surface contact therewith. Accordingly, an actual
contact area between the covering member contact surface 21b and
the ESC covering member 22 occupies only about 1% of a surface area
of the covering member contact surface 21b. As a result, the heat
is hardly transferred from the outer focus ring member 21 to the
ESC covering member 22.
[0059] In accordance with the focus ring 19 serving as the
ring-shaped component for use in plasma processing of this
embodiment, the outer focus ring member 21 is provided with the
thin portion by forming the ring groove 34 having a ring shape
concentric with the outer focus ring member 21 on the covering
member contact surface 21b of the outer focus ring member 21.
Consequently, the outer focus ring member 21 has a smaller volume
than the conventional outer focus ring member 21 and thus has a
smaller heat capacity. In case the heat capacity is small, it is
possible to sharply increase the temperature thereof by absorbing
heat from the plasma during the plasma processing and further to
easily maintain the high temperature. Thus, the deposits adhered to
the outer focus ring member 21 can be rapidly removed and, also,
the state in which the deposits are hardly deposited can be
maintained. Accordingly, the deposits adhered to the outer focus
ring member 21 can be removed at the earliest processing stage of
the production lot and, thereafter the deposits can be prevented
from being adhered to the outer focus ring member 21. As a result,
it is possible to avoid a deterioration of the wafer production
yield and lengthen the cleaning cycle of the focus ring 19.
[0060] In the outer focus ring member 21, only the ring groove 34
is formed on the covering member contact surface 21b, which is a
simple machining process. Thus, the outer focus ring member 21 can
be manufactured at a low cost, allowing a running cost to be
reduced. Moreover, since the outer focus ring member 21 can be
easily replaced, it is possible to avoid a deterioration of the
maintenability. Consequently, the focus ring 19 can be easily used
in the plasma processing apparatus 10.
[0061] In order to reduce the heat capacity, it is preferable to
minimize the thickness of the outer focus ring member 21. However,
if the thickness is excessively thin, e.g., about 1 mm, the outer
focus ring member 21 may get easily damaged. In the aforementioned
focus ring 19, the thickness between the plasma exposure surface
21a of the outer focus ring member 21 and the bottom portion 34a of
the ring groove 34 is from about 1.5 mm to about 2.0 mm, ensuring
the stiffness of the outer focus ring member 21 to be preserved to
thereby prevent the outer focus ring member 21 from being
damaged.
[0062] Although the aforementioned focus ring 19 has the outer
focus ring member 21 made of quartz, the material for the outer
focus ring member 21 is not limited thereto. The outer focus ring
member 21 can be made of any one of quartz, carbon, silicon,
ceramic (yttrium oxide (Y.sub.2O.sub.3) or silica) or the like.
Since any of those materials are easily obtainable, the focus ring
19 can be manufactured at a low cost and thus used with less
reservation given to the cost issue.
[0063] In the aforementioned focus ring 19, a single groove is
formed on the covering member contact surface 21b of the outer
focus ring member 21. However, the number of grooves is not limited
thereto but can vary as long as it is possible to properly set the
heat capacity of the outer focus ring member 21. For example, two
grooves can be formed thereon (see FIG. 4A). Moreover, a cross
sectional shape of the groove can vary without being limited to the
rectangular shape. In order to ensure that it is to be strong
enough, the groove is preferably formed in a circular arc shape,
for example.
[0064] Besides, in the aforementioned focus ring 19, the thick
portions formed at the inner side and the outer side of the thin
portion. Therefore, even if the outer focus ring member 21 is
consumed by the ions or the like colliding therewith, sharp-edged
portions are not formed at an inner and an outer peripheral portion
of the outer focus ring member 21, preventing an operator from
being injured by the sharp-edged portions. Further, a second moment
of area can be ensured, so that the stiffness of the outer focus
ring member 21 can be improved.
[0065] In addition, in the focus ring 19, the outer focus ring
member 21 has the ring groove 34 formed on the covering member
contact surface 21b, so that the outer focus ring member 21 can be
accurately mounted on the ESC covering member 22 without
misaligning the plasma exposure surface 21a and the covering member
contact surface 21b.
[0066] Hereinafter, a plasma processing apparatus employing a
ring-shaped component for use in plasma processing in accordance
with a second preferred embodiment will be described.
[0067] This embodiment has the same configuration and operation as
those of the first embodiment, except for the focus ring structure
thereof. Therefore, the description of repeated configuration and
operation will be omitted and only the difference will be described
hereinafter.
[0068] FIG. 3 provides an enlarged cross sectional view around a
focus ring employed in a plasma processing apparatus as the
ring-shaped component for use in plasma processing in accordance
with the second preferred embodiment of the present invention.
[0069] Referring to FIG. 3, the focus ring 36 includes an inner
focus ring member 20 and an outer focus ring member 37 provided to
surround an outer periphery of the inner focus ring member 20. The
outer focus ring member 37 is formed of two laminated round
ring-shaped plate members, i.e., a lower outer focus ring plate 39
and an upper outer focus ring plate 40. Since the lower and the
upper outer focus ring plates 39 and 40 are all made of an
insulating material, e.g., quartz, the outer focus ring member 37
also serves as an insulator for confining the plasma on the wafer
W.
[0070] In the outer focus ring member 37, the lower outer focus
ring plate 39 is mounted on the ESC covering member 22 and the
upper outer focus ring plate 40 is mounted on the lower outer focus
ring plate 39. Therefore, a upper surface 40a (first surface) of
the upper outer focus ring plate 40 faces the processing space S.
Accordingly, most of the deposits get adhered onto the upper
surface 40a of the upper outer focus ring plate 40 during the
plasma processing of the dummy wafer.
[0071] The lower and the upper outer focus ring plates 39 and
respectively have uniform thicknesses from inner peripheral
portions to vicinities of outer peripheral portions. Specifically,
the upper outer focus ring plate 40 has a thickness of about 1.5 mm
to about 2.0 mm. Accordingly, the upper outer focus ring plate 40
has a smaller volume than the conventional outer focus ring member
having a thickness of 3.5 mm and thus has a smaller heat
capacity.
[0072] Since the upper outer focus ring plate 40 is also formed by
cutting a pure quartz material, its surface is not smooth but it
has a rough surface covered with fine protrusions formed thereby.
Thus, the upper outer focus ring plate 40 is in, e.g, point contact
with the lower outer focus ring plate 39 via the multiple
protrusions without being in surface contact therewith.
Accordingly, an actual contact area between the upper outer focus
ring plate 40 and the lower outer focus ring plate 39 occupies only
about 1% of a surface area of a lower surface 40b (second surface)
of the upper outer focus ring plate 40 which faces an opposite side
of the processing space S side. As a result, the heat is hardly
transferred from the upper outer focus ring plate 40 to the lower
outer focus ring plate 39.
[0073] In accordance with the focus ring 19 serving as a
ring-shaped component for use in plasma processing of this
embodiment, the outer focus ring member 37 is formed of the two
laminated round-ring shaped plate members, i.e., the lower outer
focus ring plate 39 and the upper outer focus ring plate 40. Thus,
the upper outer focus ring plate 40 can be made thinner than the
conventional outer focus ring member. Accordingly, the upper outer
focus ring plate 40 has a smaller volume than the conventional
focus ring and thus has a smaller heat capacity. In case the heat
capacity is small, it is possible to rapidly increase a temperature
by absorbing heat from the plasma during the plasma processing and
further to easily maintain the high temperature. Therefore, the
deposits adhered to the upper outer focus ring plate 40 can be
rapidly removed and, also, the state in which the deposits are
hardly deposited can be maintained. Hence, the deposits adhered to
the upper outer focus ring plate 40 can be removed at the earliest
processing stage of the production lot and, thereafter, the
deposits can be prevented from being adhered to the upper outer
focus ring plate 40. As a result, it is possible to avoid a
deterioration of the wafer production yield and lengthen the
cleaning cycle of the focus ring 36.
[0074] Further, since only the lower and the upper outer focus ring
plates 39 and 40 are laminated in the outer focus ring member 37,
the configuration thereof is simple. Thus, the outer focus ring
member 37 can be manufactured at a low cost, allowing the running
cost to be reduced. Moreover, since the outer focus ring member 37
can be easily replaced, it is possible to avoid a deterioration of
the maintenability. Consequently, the focus ring 36 can be easily
adopted in the plasma processing apparatus 10.
[0075] In order to reduce the heat capacity, it is preferable to
minimize a thickness of the upper outer focus ring plate 40.
However, if the thickness is set to be excessively thin, e.g.,
about 1 mm, the upper outer focus ring plate 40 may get easily
damaged. According to the aforementioned focus ring 36, the upper
outer focus ring plate 40 has a thickness between about 1.5 mm and
about 2.0 mm, ensuring the stiffness of the upper outer focus ring
plate 40 to be preserved to thereby prevent the upper outer focus
ring plate 40 from being easily damaged.
[0076] Although the aforementioned focus ring 36 has the outer
focus ring member 37 made of quartz in the aforementioned focus
ring 36, the outer focus ring member 37 can be made of any one of
quartz, carbon, silicon, ceramic or the like without being limited
thereto, as in case of the focus ring 19 of the first
embodiment.
[0077] The outer focus ring member 37 of the focus ring 36 is
formed of the two laminated circular ring-shaped plate members.
However, the lamination number is not limited thereto but can vary
as long as it is possible to properly set the heat capacity of the
upper outer focus ring plate and also ensure the stiffness thereof.
For example, three circular ring-shaped plate members may be
laminated (see FIG. 4B).
[0078] In the aforementioned embodiments, the circular ring-shaped
component for use in plasma processing of the present invention is
applied to the focus ring. However, the circular ring-shaped
component for use in plasma processing of the present invention can
be applied to other components for use in plasma processing, e.g.,
a shield ring (see a shield ring 71 of a plasma processing
apparatus 70 shown in FIG. 7). Moreover, such other components for
use in plasma processing can have any shapes without being limited
to the circular ring shape.
[0079] Although a plasma processing apparatus employed in the
aforementioned embodiments is an etching apparatus, the present
invention can be applied to any plasma processing apparatus having
a circular ring-shaped component installed in a processing chamber,
e.g., a CVD processing apparatus.
[0080] A substrate to be subjected to a plasma processing in the
plasma processing apparatus of the aforementioned embodiments is
not limited to a wafer for producing semiconductor devices but can
be a substrate for use in a LCD (liquid crystal display), a FPD
(flat panel display) or the like. It can also be a photo mask, a CD
substrate, printed circuit board or the like.
EXAMPLES
[0081] Hereinafter, examples of the present invention will be
described in detail.
Example 1
[0082] As for a focus ring installed the plasma processing
apparatus 10, the focus ring 36 of the aforementioned second
embodiment was employed. Herein, the upper outer focus ring plate
40 of the outer focus ring member 37 was set to have a thickness of
1.7 mm.
[0083] Next, a plasma processing was conducted, which includes: the
first step of performing the plasma processing on a wafer with a
processing gas of CF.sub.4/Ar/CO; the second step of performing the
plasma processing on the wafer with a processing gas of
C.sub.4F.sub.8/CO/Ar; the third step of performing the plasma
processing on the wafer with a processing gas of Ar/O.sub.2; and
the fourth step of performing the plasma processing on the wafer
with a processing gas of CHF.sub.3/Ar/O.sub.2.
[0084] Then the number of particles having a diameter greater than
0.20 .mu.m which are adhered to a surface of the plasma-processed
wafer was measured at every specific high frequency power
application elapsed time. FIG. 5 provides a graph illustrating a
relationship between the high frequency power application elapsed
time and the number of measured particles.
Comparative Example 1
[0085] As for a focus ring accommodated in the plasma processing
apparatus 10, a conventional focus ring having a thickness of 3.5
mm was employed.
[0086] Thereafter, by performing the plasma processing same as that
of the Example 1, the number of particles having a diameter greater
than 0.20 .mu.m which are adhered to a surface of the
plasma-processed wafer was measured at every specific high
frequency power application elapsed time. FIG. 6 offers a graph
describing a relationship between the high frequency power
application elapsed time and the number of measured particles.
[0087] According to the result of comparing the graphs shown in
FIGS. 5 and 6, in the Comparative Example 1, more than 50 particles
were measured when the high frequency power application elapsed
time reached about 15 hours, the number being a threshold for
determining whether or not the focus ring should be cleaned. On the
contrary, in the Example 1, the number of measured particles
exceeds the threshold when the high frequency power application
elapsed time reached about 48 hours.
[0088] The following is an explanation for the difference described
above. In case of the Comparative Example 1, the deposits adhered
to the focus ring during the plasma processing get hardly removed
when the high frequency power application elapsed time is short.
Since, however, an adhesive strength of the deposits becomes weak
due to a thermal history followed by an elapse of the high
frequency power application elapsed time, the deposits get suddenly
peeled off when the high frequency power application elapsed time
reaches about 15 hours. On the other hand, in case of the Example
1, even when the high frequency power application elapsed time is
short, most of the deposits adhered to the upper outer focus ring
plate 40 during the plasma processing are removed by rapidly
increasing temperature of the upper outer focus ring plate 40.
Moreover, due to the thermal history followed by the increase of
the high frequency power application elapsed time, a state in which
the deposits are hardly deposited is maintained. Accordingly, the
amount of residual deposits is small and, also, the amount of
deposits does not increase, so that particles are hardly
generated.
[0089] Further, an upper outer focus ring plate 40 (Example 2)
having a thickness of 2.5 mm was installed in the plasma processing
apparatus 10 in addition to the upper outer focus ring plate 40
employed in the aforementioned Example 1 and then the plasma
processing of the aforementioned Example 1 was performed on one
lot. After that, the amount of deposits added to each ring plate
was visually checked and it was found that the amount of deposits
adhered to the upper outer focus ring plate 40 of the Example 1 was
remarkably smaller than that of the Example 2.
[0090] As a result, it was found that as the heat capacity of the
outer focus ring is reduced, the deposits can be rapidly removed
even when the high frequency power application elapsed time is
short and, also, the state in which the deposits are hardly
deposited can be easily maintained.
[0091] While the invention has been shown and described with
respect to the preferred embodiments, it will be understood by
those skilled in the art that various changes and modification may
be made without departing from the scope of the invention as
defined in the following claims.
* * * * *